(1) Field of the Invention
This invention relates to a process for imparting antibacterial and antifungal properties to cellulosic textiles. More particularly, it relates to deposition of 1-hydroxy-2-pyridinethione (hereinafter referred to as pyrithione) in cellulosic textiles in a water-insoluble form.
(2) Description of the Prior Art
Few of the many processes previously used in anti-microbial treatment of textiles have produced bacteriostatic or fungistatic activity that was found to be durable to repeated launderings. The prior art on antibacterial finishing of textiles has been reviewed by Vigo, CHEMTECH 6, 455-8 (1976).
It is well known that both pyrithione and many of its salts and metal complexes have high, broad-spectrum anti-bacterial and antifungal activity. The present invention utilizes a zinc complex of pyrithione, bis(N-oxopyridine-2-thionato)zinc(II) (hereinafter referred to as zinc pyrithione), as the antimicrobial agent. Zinc pyrithione is widely used in hair care products, and the safety of products containing it is therefore well established.
A disadvantage of zinc pyrithione for use in textile treatments is its very low solubility in water. Doerr, British Pat. No. 1,390,004, has shown that addition of a dispersion of zinc pyrithione in an aqueous solution of a quaternary ammonium compound during a rinse step of a laundering operation can give laundered fabrics a high level of antimicrobial properties. Gerstein, British Pat. No. 1,202,716, has shown that zinc pyrithione can be solubilized by adding a polyethylenimine to a suspension of the pyrithione complex in water. Grand, U.S. Pat. No. 3,940,482, described a similar process for solubilizing zinc pyrithione by adding an aliphatic polyamine of relatively low molecular weight (H.sub.2 N(CH.sub.2 CH.sub.2 NH).sub.n H, where n=1-5) to the aqueous system. The latter patent suggests that the solutions obtained are useful in compositions for treating textiles, such as diapers. However, the prior art suggests no method whereby zinc pyrithione can be used to give textiles antimicrobial properties that are durable to laundering. Zinc pyrithione deposited on a fabric surface by treatment with a dispersion of the compound would be rapidly removed by laundering. Zinc pyrithione that had been solubilized by a polyamine and then deposited in fabric by impregnating it with a zinc pyrithione solution and drying would be removed even more easily by washing or leaching. The high durability of the antibacterial activity imparted by treatment with the zinc pyrithione compositions used in the present invention is a major advantage over the processes of the prior art.